B1397

Code

Other B — Body

Power Door Unlock Circuit Short To Battery

Brand: Other

Type: B — Body

Views: UK: 29 EN: 42 RU: 26

AI status

Completed

ready

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Page language: EN

Causes

Wiring shorted to constant battery voltage
Damaged or pinched wiring harness at door hinge or body
Faulty door lock actuator with internal short
Shorted or stuck unlock switch (driver door or keyless entry)
Aftermarket alarm/remote or wiring incorrectly installed
Faulty fuse or relay (intermittent shorts)

Symptoms

Door(s) fail to unlock with switch or remote
Doors unlock unexpectedly or continuously
Blown fuse for door lock/unlock circuit
Parasitic battery drain or discharged battery
Intermittent operation or operation only after wiggling harness
Related DTCs stored for door lock/BCM circuits

What to check

Scan for B1397 and any related door/BCM codes; note freeze/frame data
Visually inspect fuses and relays for the lock/unlock circuit
Inspect wiring and connectors at door hinge (flex boot) and actuator
Operate unlock while observing connector for voltage or arcing
Disconnect door actuator and test if code clears or symptoms change
Check for aftermarket alarm/remote wiring tied to constant 12V

Signal parameters

Battery voltage on constant feed: ~12.0–14.5 V (engine running)
Unlock output (commanded) expected: 0 V (off) -> switched to ground or +12V depending on design when activated
When inactive, unlock circuit should not show battery voltage (should be open/high impedance or at module internal reference)
Typical actuator coil resistance: ~5–50 ohms (varies by design) — unusually low resistance may indicate short
Actuator current while operating: often 0.5–5 A peak (measure with clamp meter) — continuous high current indicates stall/short

Diagnostic algorithm

Retrieve freeze-frame and related codes. Confirm B1397 is current or stored.
Visually inspect fuses, relays, connectors and wiring in door jamb and at the actuator for damage, corrosion or pinching.
With ignition ON (or as required), backprobe the unlock circuit at the actuator connector. Check voltage while circuit is inactive — presence of battery voltage with no command indicates short to battery.
Operate unlock command (key fob or switch). Measure voltage change and current draw at the actuator. Excessive current or no change suggests actuator short or wiring fault.
Disconnect the actuator; if the short/noise/fuse/voltage condition clears with actuator disconnected, test or replace the actuator.
If actuator disconnected does not clear the short, isolate harness sections: check continuity to battery, check for short to battery using a fused jumper or current-limited power source, and wiggle test through door jamb.
Inspect for and remove any aftermarket device connections. Verify correct wiring per vehicle wiring diagram.
If wiring and actuator check good, test BCM/door module outputs with manufacturer scan tool: command unlock and monitor output state. If module output is stuck to battery, consider BCM/module fault and follow manufacturer module test/reprogram procedures.
Repair or replace damaged wiring, connectors, actuator, relay or module as indicated. Clear codes and retest multiple cycles and doors.
After repair, verify no parasitic drain and that locks operate normally under all control methods.

Likely causes

Frayed multiconductor cable in door jamb contacting battery feed
Corroded or damaged connector at door lock actuator providing battery to circuit
Actuator motor windings shorted internally to battery
Aftermarket remote unlock harness inadvertently tied to constant 12V
Unlock relay contacts welded or stuck closed
BCM driver transistor failed shorted to battery

Fault status

⚠️ Status

Stored when the unlock circuit is detected at battery potential or a direct short to battery is present on the power door unlock line. May cause inoperative or unintended unlocking, blown fuse, or battery drain.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours